The present invention concerns centrifugal processing apparatus and, more particularly, apparatus employing umbilical tubing which is rotated with respect to a stationary base.
Centrifugal processing systems are used in many fields. In one important field of use, a liquid having a suspended mass therein is subjected to centrifugal forces to obtain separation of the suspended mass.
As a more specific example, although no limitation is intended herein, in recent years the long term storage of human blood has been accomplished by separating out the plasma component of the blood and freezing the remaining red blood cell component in a liquid medium, such as glycerol. Prior to use, the glycerolized red blood cells are thawed and pumped into the centrifugating wash chamber of a centrifugal liquid processing apparatus. While the red blood cells are being held in place by centrifugation, they are washed with a saline solution which displaces the glycerol preservative. The resulting reconstituted blood is then removed from the wash chamber and packaged for use.
The aforementioned blood conditioning process, like other processes wherein a liquid is caused to flow through a suspended mass under centrifugation, necessitates the transfer of solution into and out of the rotating wash chamber while the chamber is in motion. Thus while glycerolized red blood cell and saline solution are passed into the wash chamber, waste and reconstituted blood solutions are passed from the chamber. To avoid contamination of these solutions, or exposure of persons involved in the processing operation to the solutions, the transfer operations are preferably carried out within a sealed flow system.
One type of centrifugal processing system which is well adapted for the aforementioned blood conditioning process uses the principles of operation described in Dale A. Adams U.S. Pat. No. 3,686,413. The apparatus of the Adams patent established fluid communication between a rotating chamber and stationary reservoirs through a flexible interconnecting umbilical cord without the use of rotating seals, which are expensive to manufacture and which add the possibility of contamination of the fluid being processed.
The primary embodiment of the Adams patent comprises a rotating platform which is supported above a stationary surface by means of a rotating support. A tube is connected to the stationary support along the axis of the rotating platform and the rotating support, with the tube extending through the rotating support and having one end fastened to the axis of the rotating platform. A motor drive is provided to drive both the rotating platform and the rotating support in the same relative direction at speeds in the ratio of 2:1, respectively. It has been found that by maintaining this speed ratio, the tube will be prevented from becoming twisted. An improvement with respect to this principle of operation, comprising a novel drive system for a centrifugal liquid processing system, is disclosed in Khoja, et al. U.S. Pat. No. 3,986,442. In the Khoja, et al. patent, a novel drive system is provided for driving a rotor assembly at a first speed and a rotor drive assembly at one-half the first speed, in order to prevent an umbilical tube from becoming twisted.
Typically the umbilical tube is formed of multiple lumen plastic tubing, such as plastic tubing having a circular cross-sectional configuration and defining four or five longitudinal channels. A small tube is connected to each of the walls defining each of the channels, with each of the small tubes being used to carry either the blood or the solutions used in connection with the blood.
It has been found to be desirable that the tubing have an internal diameter that is sufficiently large so as to prevent damage to the blood cells. It has also been found desirable that the channels defined by the flexible tubing have a diameter which is sufficiently large so as to enable the small tubing to be effectively fastened to the walls defining these channels. It has been found essential that the cable segment maintains sufficient integrity so that during operation of the centrifugal processing apparatus the motions of the cable segment do not cause rupture thereof.
On the other hand, cable segments having the desirable properties mentioned above have required a relatively large cross-sectional area, thereby presenting a significant load to the system during operation. Stress resulting from such substantial load has caused deterioration and fracture of the tubing and/or the components involved with the tubing. It was thus determined that a reduction in the weight of the umbilical tube would be required, without correspondingly reducing the other characteristics of the tubing so as to render the tubing incapable of handling proper blood flow and incapable of being properly assembled.
It is, therefore, an object of the invention to provide umbilical tubing for centrifugal processing apparatus, with the umbilical tubing having reduced load characteristics.
A further object of the present invention is to provide umbilical tubing for centrifugal processing apparatus, in which the umbilical tubing has a cross-sectional area at its ends which is large enough to enable effective connection of small tubing to the walls defining longitudinal channels in the umbilical tubing.
Another object of the present invention is to provide centrifugal processing apparatus in which the umbilical tubing has sufficient integrity for effective operation, yet is relatively lightweight so as to reduce the load on the system.
Other objects and advantages of the present invention will become apparent as the description proceeds.